It is well known in the art that down is the most efficient natural product that provides maximum warmth with minimal weight. Down is a fluffy material formed of clusters that trap air molecules in small pockets which create a thermal barrier. The clusters have tiny hairs that criss-cross in all directions, up to two million filaments for every ounce of down, and this structure can be compressed to be packed into very small spaces and then released to assume its natural loft. Down insulating material can breathed due to the air captured therein by the clusters. Duck, geese or swan are the only birds that can live in the r and tropics and its down provides heat in the winter time and coolness in the summer time. However, down has some drawbacks when used in free form and this has been addressed in my earlier U.S. Pat. No. 6,025,041 where I describe converting the loose down into sheet form to overcome prior problems associated with the use of down.
Among its many other qualities, down can also provide sound insulation. It is also a product that is bio-degradable. The use of down in manufactured articles also supports the farming communities.
However, down is an expensive material and during its use in manufacturing processes there is a certain percentage of waste, usually in the range of 10% to 20%. This waste material is caused during the stuffing processes or cutting processes when using down in sheet material form, as described in my above referenced patent, and when cutting pattern pieces within the down sheets. This also causes some of the tiny clusters, as described above, to be release in the air causing a health hazard to the working person. Therefore, it is important when working with down to assure that it is always maintained in a captive manner.
When using down material in products as thermal insulation, it is often necessary to provide different thickness of insulation in different part of a product. Using the stuffing method by forming pockets of different size by stitching fabric pieces together and inserting loose down in the pockets is a solution which has many disadvantages which have been addressed in the past. For instance, if the article is an article of apparel, such as a jacket, it provides bulging parts which is not eye pleasing and which provide many disadvantages when the article is washed and ages when the down material forms clumps. The use of down sheet material of my patent overcomes this problem of having to quilt fabric pieces to retain down therebetween. However, the down feather sheets are formed by depositing down cluster mixed with a binder material and heating the mixture to fuse the binder to produce a sheet of substantially constant thickness and constant thermal insulating value.
In the fabrication of thermally insulated articles of apparel, sleeping bags, duvet cover and other articles, it would be advantageous to provide such articles with insulation of different insulating values in a specific part where there is a need for less or more insulation value, such as the bkk portion of a jacket where more insulation is desired in the upper part of the back than in the lower part. Securing down panel sections of different insulation values together is a solution, but it requires more labor and a means of retaining the panel sections together. Also, doubling of panels may provide excessive use of material where it is not necessary and insufficient material where needed resulting in down material waste. Down insulation can have many different uses in commercial applications where thermal insulation is required and often to also provide sound insulation, fireproofing and other features of the insulation. Such additional features are available with my down feather sheet by adding different fibers and chemicals in the down mixture as disclosed in my earlier patents. Accordingly, down insulation may find other commercial applications if it could be produced as a panel with component parts having different insulation values, such as is required in door panels of vehicles or wall panels of aircrafts, as examples only.